Rechargeable Battery Systems and Rechargeable Battery System Operational Methods

ABSTRACT

Rechargeable battery systems and rechargeable battery system operational methods are described. According to one aspect, a rechargeable battery system includes a plurality of rechargeable battery modules coupled between a plurality of terminals, wherein the rechargeable battery modules individually comprise a plurality of rechargeable battery cells and charge balancing circuitry configured to implement, for individual ones of the rechargeable battery modules, first charge balancing operations with respect to the rechargeable battery cells of individual ones of the rechargeable battery modules, and to implement second charge balancing operations with respect to the rechargeable battery modules.

TECHNICAL FIELD

This disclosure relates to rechargeable battery systems and rechargeablebattery system operational methods.

BACKGROUND OF THE DISCLOSURE

Rechargeable batteries are being designed for and used in variedapplications with different requirements for electrical energy. Therechargeable battery systems comprise rechargeable cells which receiveelectrical energy during charging operations and supply electricalenergy to a load during discharging operations. Rechargeable cells mayhave different chemistries and may include Lithium cells in one example.The number of rechargeable cells used in different applications isvaried depending upon the requirements of the load, and the number ofcells may be numerous in some implementations, for example,transportation implementations.

Individual battery cells typically have an operational voltage, forexample, 3.2 VDC for Lithium battery cells. Depending upon theapplication of use, individual battery cells may be coupled in series toprovide electrical energy to a load at an appropriate voltage.Individual battery cells may also be coupled in parallel to supply adesired amount of charge capacity.

Balancing of the battery cells may be problematic due to differentcharacteristics of the individual battery cells. In addition, a batterycell may be damaged if its voltage gets too high or too low and may failto charge once damaged.

At least some aspects of the disclosure are directed towardsrechargeable battery systems and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the disclosure are described below withreference to the following accompanying drawings.

FIG. 1 is a functional block diagram of a rechargeable battery systemaccording to one embodiment.

FIG. 2 is a functional block diagram of a rechargeable battery systemaccording to one embodiment.

FIG. 3 is an illustrative representation of a plurality of rechargeablebattery modules according to one embodiment.

FIG. 4 is an illustrative representation of a rechargeable cell moduleaccording to one embodiment.

FIG. 5 is a graphical representation of voltage versus charge for arechargeable battery cell according to one embodiment.

FIG. 6 is a graphical representation of shunting of electrical energy ofdifferent rechargeable battery cells according to one embodiment.

FIG. 7 is a functional block diagram of a capacitor module according toone embodiment.

FIG. 8 is an illustrative representation of charge balancing of aplurality of cells of a plurality of rechargeable battery modulesaccording to one embodiment.

DETAILED DESCRIPTION OF THE DISCLOSURE

Attention is directed to the following commonly assigned applications,which are incorporated herein by reference:

U.S. Patent Application Attorney Docket VA24-001 entitled “RechargeableBattery Systems And Rechargeable Battery System Operational Methods” byinventor Peter Nysen, and filed the same day as the present application;and U.S. Patent Application Attorney Docket VA24-002 entitled“Rechargeable Battery Systems And Rechargeable Battery SystemOperational Methods” by inventor Peter Nysen, and filed the same day asthe present application.

According to one embodiment, a rechargeable battery system includes aplurality of rechargeable battery modules coupled between a plurality ofterminals, wherein the rechargeable battery modules individuallycomprise a plurality of rechargeable battery cells and charge balancingcircuitry configured to implement, for individual ones of therechargeable battery modules, first charge balancing operations withrespect to the rechargeable battery cells of individual ones of therechargeable battery modules, and to implement second charge balancingoperations with respect to the rechargeable battery modules.

According to an additional embodiment, a rechargeable battery systemoperational method comprises charging a plurality of rechargeablebattery modules individually comprising a plurality of rechargeablebattery cells, implementing first charge balancing operations withrespect to the rechargeable battery cells of individual ones of therechargeable battery modules, and implementing second charge balancingoperations with respect to the rechargeable battery modules.

According to another additional embodiment, a rechargeable batterysystem comprises a plurality of rechargeable battery cells coupledbetween a plurality of terminals and charger circuitry configured toprovide charging electrical energy to the rechargeable battery cells tocharge the rechargeable battery cells, and wherein the charger circuitryis configured to reduce an amount of the charging electrical energyprovided to charge at least the one of the rechargeable battery cellswhich has a highest state of charge compared with others of therechargeable battery cells as a result of the state of charge of the oneof the rechargeable battery cells exceeding a threshold.

According to yet another embodiment, a rechargeable battery systemoperational method comprises providing charging electrical energy to aplurality of rechargeable battery cells to charge the rechargeablebattery cells and reducing an amount of the charging electrical energyprovided to one of the rechargeable battery cells which has a higheststate of charge compared with others of the rechargeable battery cellsas a result of the state of charge of the one of the rechargeablebattery cells exceeding a threshold.

Referring to FIG. 1, a rechargeable battery system 10 is shown accordingto one embodiment. In the illustrated example, the rechargeable batterysystem 10 includes a plurality of rechargeable battery cells 12, chargercircuitry 16, charge balancing circuitry 18 and control circuitry 20.Other embodiments are possible including more, less and/or alternativecomponents.

Rechargeable battery cells 12 are configured to store electrical energywhich may be used to power load 14 during discharge operations ofbattery system 10. In one embodiment, rechargeable battery cells 12include Lithium cells. Rechargeable battery cells 12 may be arranged ina pack including different series and/or parallel arrangements indifferent configurations for use in powering different loads 14 havingdifferent power requirements. In some embodiments described below,rechargeable battery cells 12 may be implemented within a plurality ofmodules.

Charger circuitry 16 is configured to supply charging electrical energyto rechargeable battery cells 12 during charging operations of batterysystem 10. Charger circuitry 16 may provide the charging electricalenergy from any suitable source, such as AC mains, solar, fossil fuels,water, or wind in some examples.

Charge balancing circuitry 18 is configured to implement operations inan effort to increase balancing of states of charge of rechargeablecells 12. In some example embodiments described below, charge balancingcircuitry 18 includes charge shunting circuitry configured to shuntcharging electrical energy around selected ones of the rechargeablecells 12 having states of charge greater than others of the rechargeablecells 12. Charge balancing circuitry 18 may include charge shuttlingcircuitry in some embodiments. Charge shuttling circuitry of the chargebalancing circuitry 18 is configured to shuttle electrical energybetween selected ones of the rechargeable cells 12 as described indetail below.

Control circuitry 20 is configured to monitor and control operations ofbattery system 10. For example, control circuitry 20 may monitor statesof charge of the rechargeable battery cells 12 and control operations ofcharger circuitry 16 and charge balancing circuitry 18 as a result ofthe monitoring.

Control circuitry 20 may comprise circuitry configured to implementdesired programming provided by appropriate media in at least oneembodiment. For example, the control circuitry 20 may be implemented asone or more of a processor and/or other structure configured to executeexecutable instructions including, for example, software and/or firmwareinstructions, and/or hardware circuitry. As described below according tosome example embodiments, control circuitry 20 includes a systemcontroller 21 and a plurality of module controllers 120. Exemplaryembodiments of control circuitry 20 include hardware logic, PGA, FPGA,ASIC, state machines, and/or other structures alone or in combinationwith a processor. These examples of control circuitry 20 are forillustration and other configurations are possible.

Control circuitry 20 may include or otherwise access storage circuitry(not shown) which is configured to store programming such as executablecode or instructions (e.g., software and/or firmware), electronic data,databases, state of charge information, thresholds, or other digitalinformation and may include processor-usable media. Processor-usablemedia may be embodied in any computer program product(s) or article ofmanufacture(s) which can contain, store, or maintain programming, dataand/or digital information for use by or in connection with aninstruction execution system including control circuitry in theexemplary embodiment. For example, exemplary processor-usable media mayinclude any one of physical media such as electronic, magnetic, optical,electromagnetic, infrared or semiconductor media. Some more specificexamples of processor-usable media include, but are not limited to, aportable magnetic computer diskette, such as a floppy diskette, zipdisk, hard drive, random access memory, read only memory, flash memory,cache memory, and/or other configurations capable of storingprogramming, data, or other digital information.

At least some embodiments or aspects described herein may be implementedusing programming stored within appropriate storage circuitry describedabove and configured to control appropriate control circuitry 20. Forexample, programming may be provided via appropriate articles ofmanufacture including, for example, embodied within media discussedabove.

Referring to FIG. 2, one embodiment of rechargeable battery system 10 isshown in additional detail. In the depicted embodiment, rechargeablebattery cells 12 are arranged in an appropriate pack to provideelectrical energy to power load 14.

Control circuitry 12 includes a system controller 21 which providesmonitoring and control of battery system 12 at a system level. Systemcontroller 21 may communicate with a plurality of module controllers 120(described below with respect to FIG. 7) of a plurality of rechargeablebattery modules in one embodiment. System controller 21 is configured tomonitor an amount of electrical energy provided from rechargeablebattery cells 12 to load 14 and/or provided from charger circuitry 16 tocells 12 via current sensor 31 in the illustrated embodiment.Furthermore, system controller 21 controls a plurality of switches 24,26, 28, 30 described below.

User interface 22 is configured to interact with a user includingconveying data to a user (e.g., displaying data for observation by theuser, audibly communicating data to a user, etc.) as well as receivinginputs from the user (e.g., tactile input, voice instruction, etc.).Accordingly, in one exemplary embodiment, the user interface may includea display (e.g., cathode ray tube, LCD, etc.) configured to depictvisual information and an audio system as well as a keyboard, mouseand/or other input device. Any other suitable apparatus for interactingwith a user may also be utilized. A user may input instructions andmonitor operations of battery system 10 via user interface 22 in oneembodiment.

In one embodiment, system controller 21 is configured to controlcharging operations of the rechargeable battery cells 12. Systemcontroller 21 may control a switch (e.g., charging relay) 24 toselectively couple the charger circuitry 16 with the positive terminalof the pack of the rechargeable battery cells 12 at appropriate momentsin time to charge the rechargeable battery cells 12. Charger circuitry16 may be implemented as a programmable power supply which may bevoltage or current controlled in example embodiments.

In the depicted embodiment, battery system 10 also includes a switch(e.g., precharge relay) 26 and positive and negative switches (e.g.,high power relays) 28, 30. Initially, the load 14 is isolated from thepack of rechargeable battery cells 12 by switches 26, 28, 30 duringcoupling of load 14 with the rechargeable battery system 10. Followingcoupling of load 14 with the rechargeable battery system 10, theswitches 26, 28 may be initially closed by system controller 21 toprotect the battery system 10 from large current spikes. For example,switch 26 is coupled with an appropriate precharge load 32, such as anappropriate resistive load, to prevent in-rush of excessive current toload 14. Thereafter, the switch 30 may be closed to fully couple theload 14 with the pack of rechargeable battery cells 12. An appropriatefuse 34 may also be used to protect rechargeable battery system 10 fromshort circuits and other faults in load 14.

Referring to FIG. 3, a plurality of rechargeable battery modules 40 ofbattery system 10 are shown in one embodiment.

In the depicted embodiment, each of the rechargeable battery modules 40includes a positive terminal 50 and negative terminal 52 and therechargeable battery modules 40 are coupled in series. The positiveterminal 50 of the lower module 40 is the positive terminal of the packof the rechargeable battery cells 12 which may be coupled with the load14 while the negative terminal of the upper module 40 is the negativeterminal of the pack of the rechargeable battery cells 12 which may becoupled with the load 14. In addition, the positive terminal 50 of theupper module 40 and the negative terminal 52 of the lower module 40 arecoupled with one another to provide the series coupling of the modules40 in the illustrated example. Additional rechargeable battery modules40 may be provided in the rechargeable battery pack in other examples ofthe battery system 10. Furthermore, the rechargeable battery cells 12may be implemented in a pack without modules 40 in other embodiments.

Individual ones of the rechargeable battery modules 40 include aplurality of rechargeable cell modules 41 which are described below inadditional detail in the example of FIG. 4. Each rechargeable cellmodule 41 may include a rechargeable battery cell 12 coupledintermediate a plurality of terminals of the rechargeable cell module41. In addition, the rechargeable cell modules 41 of a module 40 arecoupled in series intermediate module terminals 50, 52. Although fourrechargeable cell modules 41 are coupled in series in the illustratedexamples of rechargeable battery module 40, rechargeable battery modules40 may include more or less cell modules 41 in other embodiments.

Each of the rechargeable cell modules 41 also includes a capacitorterminal labeled “C” in FIGS. 3 and 4. The capacitor terminals of therechargeable cell modules 41 are alternatively coupled with a positivecapacitor terminal 44 and a negative capacitor terminal 46 of acapacitor bus 42 of the respective rechargeable battery module 40. Thepositive and negative capacitor terminals 44, 46 of capacitor bus 42 arecoupled with respective terminals P1, N1 of a capacitor module 48 in arespective rechargeable battery module 40. The capacitor bus 42 andcapacitor module 48 may be a part of charge shuttling circuitry 64described below in one embodiment. Charge shuttling circuitry 64 isconfigured to shuttle electrical energy from one of the rechargeablecell modules 41 to another of the rechargeable cell modules 41 and/orbetween rechargeable battery modules 40 in one embodiment. The capacitormodules 48 of rechargeable battery modules 40 may be coupled with oneanother in parallel via respective terminals P2, N2 in one embodiment.

Referring to FIG. 4, one embodiment of a rechargeable cell module 41 isshown. The example embodiment of the rechargeable cell module 41 shownin FIG. 4 includes a rechargeable battery cell 12 coupled with positiveand negative terminals of the cell module 41. The illustratedrechargeable cell module 41 also includes a temperature sensor 66 whichmay be coupled with a module controller of the control circuitry 20described below (e.g., module controller 120 of FIG. 7). Temperaturesensor 66 provides signals regarding the temperature of rechargeablebattery cell 12 in the illustrated embodiment. In one embodiment,control circuitry 20 may provide a system shutdown of battery system 10if a temperature of a rechargeable battery cell 12 goes below or above adesired operational range where the cell 12 may be damaged. In oneexample where the rechargeable battery cell 12 comprises Lithium, it isdesired to maintain the cell within temperature ranges of 0 to 45° C.during charging, −10 to 50° C. during discharging, and −40 to 50° C.during storage. Furthermore, control circuitry 20 may also utilizeinformation regarding the temperature of cell 12 to determine the stateof charge of the cell 12 inasmuch as perceived state of charge may varywith the temperature of the cell 12 in some cell configurations.

The rechargeable cell module 41 also includes charge balancing circuitry60 which includes shunting circuitry 62 and charge shuttling circuitry64 in the illustrated embodiment. Charge balancing circuitry 60 attemptsto balance the states of charge of the rechargeable battery cells 12(i.e., provide the cells 12 having substantially the same state ofcharge) of the rechargeable battery modules 40 during operations of thebattery system 12.

As mentioned above with respect to some embodiments, rechargeablebattery cells 12 may be implemented as Lithium cells. Accordingly, it isdesired to avoid one or more of the rechargeable battery cells 12 havinga voltage above or below operational threshold voltages which may damagethe cell 12 in some embodiments. It is desired to provide therechargeable battery cells 12 having substantially balanced (i.e., thesame) states of charge during charging and discharging operations of thebattery system 10 which may result in an increase of the rate at whichthe battery system 10 is charged to full capacity while maximizing anamount of energy extracted from the pack of rechargeable battery cells12 during discharge operations as described further below.

Shunting circuitry 62 and shuttling circuitry 64 may be selectivelyenabled and disabled responsive to control of a respective modulecontroller of the control circuitry 20 in one embodiment in attempts tobalance the states of charge of the rechargeable battery cells 12.Shunting circuitry 62 is configured to shunt charging electrical energyfrom charger circuitry 16 around the rechargeable battery cell 12 in theillustrated embodiment. Charge shuttling circuitry 64 is configured toprovide electrical energy to the rechargeable battery cell 12 or removeelectrical energy from cell 12 during charge shuttling operations asdescribed in further detail below.

Example operations of shunting circuitry 62 are also described below. Asmentioned above, shunting circuitry 62 is configured to selectivelyshunt charging electrical energy around rechargeable battery cell 12.During charging operations, the rechargeable battery cells 12 in abattery module 40 may charge at different rates, for example, due todifferent characteristics, such as different internal resistancesresulting from manufacture of the rechargeable battery cells 12.Accordingly, one or more of the rechargeable battery cells 12 may chargefaster than others of the cells 12. In order to avoid overcharging arespective cell 12, the shunting circuitry 62 operates to shunt at leastsome or all of the charging electrical energy around the respectiverechargeable battery cell 12 of the respective rechargeable cell module41. In some embodiments, a module controller of the control circuitry 20monitors the voltages of the rechargeable battery cells 41 of therespective module 40 and controls the shunting circuitry 62 to shuntcharging electrical energy around one or more of the rechargeablebattery cells 12 having states of charge higher than another of cells 12of the module 40.

Referring to FIG. 5, a voltage versus charge graph 140 is shown fortypical Lithium cells 12. Lithium cells 12 have a plurality of differentoperational states corresponding to different states of charge of cell12. In the illustrated graph 140, a Lithium cell 12 has a substantiallydischarged state 142, an intermediate state 144 and a substantiallycharged state 146. The intermediate state 144 has a relatively flatvoltage curve versus a relatively large portion of the different statesof charge of the cell 12 while the substantially discharged and chargedstates 142, 146 have steeper slopes. It may be more difficult toaccurately determine the state of charge of the rechargeable batterycell 12 having a voltage corresponding to the intermediate state 144compared with the substantially charged and discharged states 142, 146due to the relatively flat nature of graph 140 within the intermediatestate 144.

Some drawbacks with shunting of the charging electrical energy are thatsome energy may be wasted reducing efficiency of charging operations,excessive heat, and implementing balancing operations by shunting may berelatively slow. In some arrangements, the shunting of chargingelectrical energy around one or more of the rechargeable battery cells12 having the highest states of charge may be performed during alloperational states 142, 144, 146 of the rechargeable battery cells 12 inan effort to increase the rate at which the cells 12 are balanced.

More specifically, in one embodiment, the control circuitry 20 monitorsthe states of charge of each of the rechargeable battery cells 12 of therespective module 40 during charging in all of the different operationalstates of the rechargeable battery cells 12 including the substantiallydischarged state 142, intermediate state 144 and substantially chargedstate 146, and controls the shunting of the charging electrical energyaround individual ones of the rechargeable battery cells 12 havinghigher states of charge compared with others of the cells 12 of therespective module 40 during charging in each of the differentoperational states 142, 144, 146 of the cells 12.

Even though the use of shunting circuitry 62 may be relatively slow toimplement balancing compared with other balancing techniques,implementing of shunting operations during an entirety of a chargingcycle of the rechargeable battery cells 12 of a rechargeable batterymodule 40 from the substantially discharged state 142 to theintermediate state 144 and the substantially charged state 146 improvesthe speed of the overall balancing operations since the shunting isperformed over a longer period of time compared with arrangements whichonly implement shunting operations at the end of the charging cycle toavoid overcharging one or more rechargeable battery cells having ahigher state of charge.

In one embodiment, implementing shunting operations with respect to thecharging electrical energy by the shunting circuitry 62 during each ofthe different operational states 142, 144, 146 of the rechargeable cells12 results in the rechargeable battery cells 12 entering thesubstantially charged state 146 having states of charge which are closerto one another (i.e., increased balancing) compared with arrangementswhere shunting is only performed when the cells are in the substantiallycharged state to avoid overcharge of one or more cells or shunting isnot performed at all.

The implementing of shunting operations during the different operationalstates 142, 144, 146 of the cells 12 in accordance with one describedembodiment permits shunting using reduced duty cycles (e.g., duty cycleswithin a range of 0-50%) compared with arrangements which only implementshunting when the cells are substantially charged. More specifically,the shunting during the plurality of operational states 142, 144, 146enables shunting operations to occur over longer periods of timecompared with arrangements which only implement shunting when the cellsare substantially charged, and accordingly the duty cycles of the pulsewidth modulation signals may be reduced during the balancing operationsof the cells 12 which assists with providing reduced temperatures in theshunting circuitry 62.

Referring again to FIG. 4, the example embodiment of the shuntingcircuitry 62 of an individual rechargeable battery module 41 includes ashunting device (e.g., a switch) 70, isolation circuitry 72, a load 74and a temperature sensor 76. The module controller of control circuitry20 may provide appropriate control signals via isolation circuitry 72which may implement optical, transformer coupling or Galvanic isolationin example embodiments. The control signals selectively enable shuntingdevice 70 to implement shunting operations where at least some of thecharging electrical energy passes around the rechargeable battery cell12 and through the load 74 which may be a current limiting resistor inone example. In another possible embodiment, the shunting device 70 maybe implemented as a Darlington transistor and the load 74 may beomitted.

The module controller of the control circuitry 20 may monitor thetemperature of the load 74 (or Darlington transistor not shown) via atemperature sensor 76 in one embodiment. The control circuitry 20 maydisable shunting operations of a respective shunting device 70 if thetemperature of the load 74 exceeds a threshold in one embodiment.Maximum operational temperatures of the shunting circuitry 62 maycorrespond to a maximum operational junction temperature of the shuntingdevice 70 and/or a maximum operational temperature of load 74 inillustrative embodiments. Thereafter, the shunting device 70 will remaindisabled until the temperature of the shunting device 70 falls below adifferent temperature threshold (e.g., five degrees less than thethreshold which controls the disabling of the shunting operations in oneexample). The shunting device 70 may resume shunting operations once thetemperature of the respective shunting device 70 falls below the lowertemperature threshold. In some implementations, the shunting circuitry62 may include a heat sink (not shown) to facilitate cooling of theshunting circuitry 62.

In one embodiment, the duty cycles of the pulse width modulation signalswhich are used to control the shunting may also be varied as a result ofmonitoring of the temperatures of the respective shunting circuitry 62.For example, the duty cycle of the pulse width modulation for one of theshunting circuits 62 may be reduced if the temperature of the respectiveshunting circuit 62 is approaching the temperature threshold. Loweringof the duty cycle should assist with reducing temperature of theshunting circuit 62.

Furthermore, the module controller may also monitor the temperature ofthe rechargeable battery cell 12 via temperature sensor 66 to verifythat the temperature of the cell 12 is within desired threshold limitsto avoid damage to cell 12 as mentioned above. The module controller mayinitiate a warning or perhaps shutdown charging or dischargingoperations with respect to a cell 12 having a temperature which exceedsthe threshold in example embodiments.

As mentioned previously, the module controller of the control circuitry20 may control shunting operations of the shunting circuitry 62 in oneimplementation. More specifically, the control circuitry 20 may controlthe shunting circuitry 62 of the different rechargeable cell modules 41to provide different amounts of shunting of the respective cells 12based upon the states of charge of the rechargeable battery cells 12according to one embodiment. For example, referring to FIG. 6, a graph150 illustrates different cells 12 of a module 40 having differentstates of charge at a common moment in time during a charging cycle ofthe rechargeable battery module 40. The shunting circuitry 62 of therechargeable cell modules 41 with rechargeable battery cells 12 havingthe higher states of charge may be controlled to implement increasedshunting compared with rechargeable battery cells of the module 40having less states of charge.

In one embodiment, the module controller of the control circuitry 20 isconfigured to provide pulse width modulation signals to control theshunting circuitry 62 of the individual rechargeable cell modules 41.The control circuitry 20 may vary the duty cycles of the control signalsfor the different shunting circuits 62 of the battery cell modules 41from 0-100% (0-50% in the example of FIG. 6) depending upon the statesof charge of the respective rechargeable battery cells 12 of module 40compared with others of the cells of the individual rechargeable batterymodule 40.

Increasing the duty cycle of the control signal applied to a shuntingdevice 70 operates to increase the shunting of the charging electricalenergy around the respective rechargeable battery cell 12 and reducesthe rate of charging of the cell 12 compared with rates of charge of theother cells 12 being shunted using control signals having smaller dutycycles.

In one implementation, the cells 12 having the highest and lowest statesof charge for a given rechargeable battery module 40 may be used todefine a substantially linear slope and the cell 12 having the higheststate of charge may be shunted the most (e.g., 50% duty cycle) while thecell 12 having the lowest state of charge may be shunted the least(e.g., 0% duty cycle). The pulse width modulation signals to controlshunting for others of the cells 12 may be adjusted depending upon therespective states of charge of the cells 12 between the cells 12 havingthe minimum and maximum states of charge in one example.

In one embodiment, different ranges of duty cycles may be used toimplement the shunting depending upon different states of charge of thecells 12. In one more specific example, shunting may be implementedwithin a duty cycle range of 0-50% for cells 12 which are in asubstantially discharged state or intermediate state while a duty cyclerange of 0-100% may be used for cells 12 which are in a substantiallycharged state.

In one embodiment, the module controller of a respective rechargeablebattery module 40 may determine the appropriate pulse width modulationcontrol signals for controlling the shunting circuitry 62 of therespective rechargeable cell modules 41 in accordance with the above.

In addition, states of charge of the cells 12 may be monitored withrespect to a plurality of thresholds by the control circuitry 20 duringcharging of the cells 12 in one embodiment. The thresholds which areused may correspond to the type of cells 12 which are implemented in thebattery system 10 in one embodiment. The control circuitry 20 maycontrol the charging of the cells 12 differently depending upon thestates of charge of the cells 12. In one embodiment, the controlcircuitry 20 may monitor the states of charge of individual ones of thecells 12 with respect to an initial overvoltage threshold. If all of thecells 12 of all modules 40 are below the initial overvoltage threshold,the control circuitry 20 may control the charger circuitry 16 to chargethe cells 12 of the modules 40 at a maximum charging rate using maximumcurrent.

As a result of the state of charge of a highest one of the cells 12exceeding the initial overvoltage threshold, the control circuitry 20may control the charger circuitry 16 to reduce a current of the chargingelectrical energy applied to the cells 12 of the modules 40 to be anamount less than the maximum charging current. If one of the cells 12exceeds another overvoltage threshold which is higher than the initialovervoltage threshold, the control circuitry 20 may control the chargercircuitry 16 to further reduce the current of the charging electricalenergy applied to the cells 12 of the modules 40. If one of the cells 12thereafter exceeds a fault limit threshold (which indicates a higherstate of charge than the previous thresholds), the control circuitry 20may control the charger circuitry 16 to stop providing chargingelectrical energy to the cells 12 of the modules 40.

In one embodiment, the control circuitry 20 may control the respectiveshunting circuitry 62 of the modules 41 to reduce the state of charge ofthe highest charged cell(s) 12 below the respective thresholds. Thecontrol circuitry 20 may control the shunting circuitry 62 to providemaximum shunting to cell(s) 12 which exceeded the fault limit thresholdin one embodiment. For example, the shunting devices of the appropriateshunting circuits 62 may be shunted hard on without modulation toprovide continuous maximum shunting in one embodiment. Charging may beresumed when the cell 12 which had the highest state of charge fallsbelow the cell 12 with the lowest state of charge or a timeout hasoccurred in illustrative examples.

Accordingly, the shunting causes different rechargeable battery cells 12of a battery module 40 to charge at different rates where the cells 12having less states of charge may charge faster than the cells 12 havinggreater states of charge. As mentioned above, the operations of theshunting circuitry 62 of the individual rechargeable cell modules 41during the different operational states 142, 144, 146 provides therechargeable battery cells 12 having increased balancing during chargingoperations compared with arrangements where shunting is not implementedduring the different operational states 142, 144, 146. In oneembodiment, the shunting operations enable charging of each of therechargeable battery cells 12 of a rechargeable battery module 40 to acompletely charged state faster than charging operations which do notimplement shunting operations during each of the operational states ofthe rechargeable battery cells 12 since the rechargeable cells 12 arecloser in charge to one another as the cells 12 reach substantiallycharged states of charge and significant shunting is typically notneeded to balance a significantly out of balance cell 12 with others ofthe cells 12 which are substantially charged (which may be a relativelyslow process) and which may occur in arrangements which do not implementshunting during all of the operational states 142, 144, 146 of the cells12 as discussed herein in one embodiment.

However, in some situations, one or more of the rechargeable batterycells 12 may be significantly out of balance with others of the cells 12even in the presence of shunting during each of the operational states142, 144, 146 of the cells 12. For example, a rechargeable cell module41 which includes a defective rechargeable battery cell 12 may beremoved from rechargeable battery module 40 and a replacement module 41may be inserted which is significantly out of balance with respect tothe other cells 12 of the module 40. In one embodiment, charge shuttlingcircuitry 64 may be used to transfer electrical energy between selectedones of the rechargeable battery cells 12, for example, to rapidlycharge an out of balance cell 12 in one embodiment. The charge shuttlingcircuitry 64 may be used alone (e.g., if charge shunting circuitry 62 isomitted or not being used) or in combination with the shunting circuitry62 in a hybrid arrangement or with other charge balancing circuitry inexample embodiments.

In the illustrated embodiment, individual ones of the rechargeable cellmodules 41 include charge shuttling circuitry 64 intermediate thenegative terminal of the module 41 and the C terminal of the module 41mentioned previously. As described below, the charge shuttling circuitry64 is selectively enabled by the module controller to selectively coupleone of the rechargeable battery cells 12 with the capacitor bus 42 atdifferent moments in time to shuttle electrical energy between differentones of the rechargeable battery cells 12. The module controller mayissue control signals via isolation circuitry 82 (e.g., optical,transformer coupling or Galvanic isolation) to control the operations ofswitches 80 to selectively couple the respective rechargeable batterycell 12 with the capacitor bus 46. Switches 80 are arranged to permitcurrent flow in both directions through the charge shuttling circuitry64 since alternating rechargeable battery cells 12 are reversed indirection with respect to the capacitor bus 42 as connected by the Cterminals of the rechargeable cell modules 41 and electrical energy maybe transferred to or from the respective cell 12 during shuttlingoperations. Although switches 80 are implemented as FETs in the depictedembodiment, the switches 80 may be implemented using alternativeconfigurations, such as a single relay, in other embodiments. Thecontrol signals of the switches 80 may be pulse width modulated by thecontrol circuitry 20 to provide a desired amount of current flow in oneembodiment.

In one embodiment, only one of the rechargeable battery cells 12 iscoupled with the capacitor bus 14 at a given moment in time to avoidshorting of the cells 12. The module controller is configured to monitorthe states of charge of the rechargeable battery cells 12 of therespective rechargeable battery module 40. The module controller maycontrol the shuttling circuitry 64 of appropriate ones of therechargeable cell modules 41 to transfer electrical charge from one ofthe rechargeable battery cells 12 having a highest state of charge ofthe module 40 to the one of the rechargeable battery cells 12 having alowest state of charge of the module 40 to shuttle electrical energy inone embodiment. Shuttling circuitry 64 may operate to shuttle theelectrical energy during charging and/or discharging operations indifferent embodiments.

More specifically, in one embodiment, the module controller initiallycouples the rechargeable battery cell 12 having the highest state ofcharge with the capacitor bus 42 using the C terminal and switches 80 ofthe rechargeable cell module 41 containing the cell 12 having thehighest state of charge and the C terminal and switches 80 of theadjacent module 41 which is coupled with the positive terminal of themodule 41 which contains the cell 12 having the highest state of charge.The positive terminal of the rightmost rechargeable cell module 41 maybe coupled directly with the capacitor module 48 while the negativeterminal of the rightmost module 41 may be coupled with the capacitorbus 42 via its respective C terminal and switches 80 to enable therightmost module 41 to transfer electrical energy with respect to thecapacitor module 48 in the disclosed example embodiment.

Electrical energy from the highest cell 12 is transferred to and storedwithin the capacitor module 48 as described below in one embodiment.Thereafter, the rechargeable battery cell 12 is de-coupled from thecapacitor bus 42 after the transfer of the charge to the capacitormodule 48 by disabling the C terminals.

Following the de-coupling of the initial rechargeable battery cell 12,the rechargeable battery cell 12 having the lowest state of charge ofthe module 40 is coupled with the capacitor bus 42 to receive theelectrical energy stored within the capacitor module 48 using the Cterminal and switches 80 of the rechargeable cell module 41 containingthe cell 12 having the lowest state of charge and the C terminal andswitches 80 of the adjacent module 41 coupled with the positive terminalof the module 41 which contains the cell 12 having the lowest state ofcharge. The electrical energy is transferred from the capacitor module48 to the cell 12 to increase the state of charge of the cell 12.

The result of the charge shuttling operations is to increase the stateof charge of the rechargeable battery cell 12 having the lowest state ofcharge while decreasing the state of charge of the rechargeable batterycell 12 having the highest state of charge thereby increasing thebalancing of the states of charge of the two cells 12. The chargeshuttling operations may be continually performed during differentoperational states 142, 144, 146 of the rechargeable battery cells 12during charging and discharging modes of operation. The charge shuttlingoperations operate to balance the states of charge of one or more of therechargeable battery cells 12 which are significantly out of balancewith others of the cells 12 in a manner which is faster and moreefficient than use of the shunting circuitry 62, for example.Furthermore, the capacitor modules 48 may also transfer and/or receiveelectrical energy with respect to other capacitor modules 48 of otherrechargeable battery modules 40 as described further below in someembodiments.

In one embodiment discussed above, shunting operations may be suspendedif a temperature of the shunting circuitry 62 exceeds a threshold.However, charge shuttling operations may continue to be implemented withrespect to cells 12 (e.g., shuttling charge between cells 12 having thehighest and lowest states of charge) while shunting operations aredisabled with respect to one or more of the cells 12 having anout-of-range temperature condition. In one specific embodiment,shuttling may be implemented with respect to a cell 12 whose shuntingcircuitry 62 has been disabled.

Accordingly, in one embodiment, the module controller may control theshuttling circuitry 64 to couple appropriate ones of the rechargeablebattery cells 12 with the capacitor bus 42 at different moments in time.The coupled rechargeable battery cell 12 either transfers electricalenergy to the capacitor module 48 or receives electrical energy from thecapacitor module 48 in one embodiment.

Referring to FIG. 7, an example embodiment of a capacitor module 48 ofone of the rechargeable battery modules 40 is shown. Other embodimentsare possible including more, less and/or alternative components.

Capacitor module 48 includes a module controller 120 which is a part ofcontrol circuitry 20 in the described example embodiment. Capacitormodule 48 may be considered to be a battery hub interfacing with therechargeable cells modules 41 of the respective rechargeable batterymodule 40 as well as the system controller 21 in one embodiment. Inaddition, capacitor module 48 may also provide voltage monitoring of therechargeable battery cells 12 of the respective module 40 and controlcharging of storage circuitry 90 of the respective module 40 toimplement charge shuttling operations described below. Capacitor module40 may also be used to provide parallel to serial conversion of switchand temperature control and data signals which control switches andmonitor temperatures of the respective rechargeable battery modules 40and for communications with system controller 21 in one embodiment.Capacitor modules 48 of the rechargeable battery modules 40 may also beused to couple a plurality of the rechargeable battery modules 40together, for example to implement large scale balancing (see FIG. 8) inone embodiment.

Accordingly, module controller 120 is configured to monitor and controlvarious operations of the rechargeable battery module 40 includingmonitoring and controlling operations of the rechargeable cell modules41 and capacitor module 48 of the rechargeable battery module 40 in oneembodiment. For example, in the illustrated embodiment, modulecontroller 120 may be configured to control the shuttling circuitry 64resident in the capacitor module 48 as well as control the shuttlingcircuitry 64 of the individual rechargeable cell modules 41 (e.g.,control the operations of switches 80 to selectively couple appropriaterechargeable battery cells 12 with the capacitor bus 42). In addition,the module controller 120 may control the shunting operations of theshunting circuitry 62 based upon states of charge of the cells 12 (e.g.,control the switches 70 to selectively shunt charging electrical energyaround respective ones of the rechargeable battery cells 12).

Module controller 120 is also configured to monitor temperatures of therechargeable battery cells 12 via respective temperature sensors 66 andto monitor temperatures of the shunting circuitry 62 via the respectivetemperature sensors 76. Module controller 120 is also configured tomonitor voltages (and the states of charge) of rechargeable batterycells 12 as described further below.

As mentioned above, module controller 120 is also configured tocommunicate with system controller 21 in one embodiment. Systemcontroller 21 may monitor states of charge of the rechargeable batterycells 12 of the respective rechargeable battery module 40 viacommunications with module controller 120 and also issue control signalsto control operations of module controller 120 (e.g., large scalebalancing operations) in one embodiment.

Module controller 120 may have appropriate memory 122 which containsprogramming for execution by module controller 120, data storage, etc.In one embodiment, memory 122 includes calibration information forfactory calibrating the voltage monitoring due to component valueerrors.

In the illustrated embodiment, capacitor module 48 includes a portion ofcharge shuttling circuitry 64 in the form of storage circuitry 90including plural storage devices 92 (e.g., capacitors) in one example.Storage devices 92 are configured to store electrical energy receivedfrom one of the rechargeable cell modules 41 via capacitor bus 42 and toprovide the electrical energy to another of the rechargeable cellmodules 41 via capacitor bus 42 to implement charge shuttling operationsin one embodiment.

Module controller 120 is coupled with a switch control 100 in oneembodiment to control various operations of capacitor module 48. Modulecontroller 120 may control switches 94, 99 to couple the capacitormodule 48 with different capacitor buses 42 of the rechargeable batterymodules 41 in one embodiment. Module controller 120 may control switches95, 98 to control the polarity of the coupling of a rechargeable batterycell 12 with the capacitor bus 42 in one embodiment based upon thepolarity of the coupling of the rechargeable battery cell 12 with thecapacitor bus 42 via the switches 80 and C terminals of the individualrechargeable cell modules 41 in one embodiment. Switch 97 may becontrolled to decouple storage circuitry 90 from capacitor bus 42 of themodule 40 to permit monitoring of voltages of cells 12 using voltagemonitoring circuitry 102 as described below in one embodiment.

Capacitor module 48 is also coupled with a positive terminal ofrechargeable battery module 40 in one embodiment. Module controller 120may selectively control a switch 110 via appropriate isolation circuitry124 (e.g., optical, transformer coupling or Galvanic isolation) toselectively couple the positive terminal 50 with the storage circuitry90 via a connector 112, for example, to receive or provide electricalenergy with respect to the rightmost one of the rechargeable batterymodules 41 of FIG. 3 during charge shuttling operations in oneembodiment.

In one embodiment, capacitor module 48 includes a voltage multiplicationcircuit which is configured to receive electrical energy from one of thecells 12 at a first voltage, to increase the voltage of the electricalenergy and to transfer the electrical energy having the increasedvoltage to another of the modules 41.

More specifically, a cross-over switch 96 is utilized to couple thestorage devices 92 in parallel or in series with one another withrespect to capacitor bus 42 in one embodiment. The control of theparallel or series coupling selectively provides a voltagemultiplication circuit (e.g., voltage doubler) during charge shuttlingoperations in one embodiment. For example, even though two rechargeablebattery cells 12 may have different states of charge, they may havesimilar voltages (e.g., if both cells 12 are in the intermediate stateof charge 144). Charge shuttling circuitry 64 is configured to implementa voltage doubling function in the described embodiment to control theflow of electrical energy from the rechargeable battery cell 12 havingthe higher state of charge to the cell 12 having the lower state ofcharge. The arrangement enables relatively high current flow between thecells 12 even though the cells 12 have similar voltages as discussedfurther below.

In one embodiment, module controller 120 controls the crossover switch96 to couple the storage devices 92 in parallel with one another whenelectrical energy is received from the one of the rechargeable batterycells 12 having the higher state of charge. Thereafter, the storagedevices 92 are coupled in series with one another to increase thevoltage of the stored electrical energy to cause the electrical energyto flow to the one of the rechargeable battery cells 12 coupled withcapacitor bus 42 having the lower state of charge. Storage circuitry 90may be coupled with a resistive load 91 to limit currents flowing intoand out of storage circuitry 90 in one embodiment.

This described example arrangement may provide increased current flowduring charge shuttling operations from the cell 12 having the higherstate of charge to the cell 12 having the lower state of charge comparedwith arrangements which do not use voltage multiplication circuitry.More specifically, current flow between cells 12 is reduced as thevoltage potential difference between the cells 12 decreases. However,the voltage multiplication circuitry of one embodiment of the disclosureprovides an increased voltage potential difference which providesincreased current flow during charge shuttling operations between thecells 12 (even if the cells 12 have substantially the same voltagewithout the multiplication) compared with arrangements which do notutilize the described voltage multiplication.

Capacitor module 48 is also configured to implement voltage monitoringoperations of the rechargeable battery cells 12 via voltage monitoringcircuitry 102 in one embodiment. Module controller 120 may determinestate of charge information using the determined voltages of therechargeable battery cells 12 in one embodiment.

Module controller 120 may control switch 108 to selectively couple acapacitor 104 in parallel with the capacitor bus 42 to monitor a voltageof the cell 12 of one of the modules 41 which is also coupled with thecapacitor bus 42 in example embodiments. Module controller 120 maymonitor voltages of individual ones of the rechargeable battery cells 12coupled with capacitor bus 42 at different moments in time via thecapacitor 104 and interface circuitry 106 to determine the states ofcharge of the cells 12 in one embodiment. Switches of the storagecircuitry 90 and switch 97 may be opened to de-couple storage devices 92from the capacitor bus 42 while voltage monitoring operations areperformed in one embodiment. Voltage monitoring circuitry 102 may alsobe used to monitor voltages of the storage devices 92 with the cells 12de-coupled from the capacitor bus 42 in one embodiment.

Any suitable method may be used to calculate the states of charge of thecells 12. In one embodiment, information from current sensor 31 and thevoltages of the rechargeable battery cells 12 may be used to determinethe states of charge of the rechargeable battery cells 12. Systemcontroller 21 or module controllers 120 may calculate the states ofcharge of the cells 12 in one embodiment. In one example, controlcircuitry 20 may employ Coulomb counting using current information fromsensor 31 (FIG. 2). Furthermore, monitored temperature information ofthe cells 12 may be used in one embodiment to cancel out temperatureeffects on the battery system 10 to assist with the determination of thestates of charge. Other suitable methods such as monitoring consumedpower from the cells 12 may be used to calculate states of charge of thecells 12 in other embodiments.

During voltage monitoring of cells 12, operations of shunting circuitry62 may be taken into account in one embodiment. For example, only a cell12 which is not being shunted may be considered to be a lowest chargedcell 12 while any of the cells may be considered to be a highest chargedcell 12 in one implementation.

Referring to FIG. 8, one method of balancing rechargeable battery cells12 using charge shuttling is shown. The illustrated example is performedwith respect to two rechargeable battery modules 40 of a pack of therechargeable battery cells 12 and the modules 40 each include fourrechargeable battery cells A1-A4 and B1-B4 in the example of FIG. 8. Inone embodiment, system controller 21 is configured to executeappropriate programming using information from individual modulecontrollers 120 of the rechargeable battery modules 40 to implement thedescribed balancing operations. Other methods are possible andadditional modules 40 may be balanced in other embodiments.

The balancing operations proceed from the top downwards in the exampleof FIG. 8 and the top illustration depicts states of charge of the cellswhen balancing operations are initiated. The middle illustration depictsfirst balancing operations which are performed to balance therechargeable battery cells of a given module 40 with respect to oneanother. As described below, one of the rechargeable battery cells of amodule 40 is left out of balance with the other cells of the same module12 as a result of the first balancing operations. Thereafter, the chargeshuttling circuitry 64 may implement second balancing operations tobalance the states of charge of plural modules 40 with respect to oneanother.

The charge balancing circuitry 64 is configured to implement, forindividual ones of the rechargeable battery modules 40, the first chargebalancing operations to increase the balancing of states of charge ofthe rechargeable battery cells of one of the rechargeable batterymodules 40 compared with the states of charge of the rechargeablebattery cells of the respective rechargeable battery modules 40 in anabsence of the first charge balancing operations. The charge balancingcircuitry 64 is also configured to implement the second charge balancingoperations to increase the balancing of states of charge of therechargeable battery modules 40 with respect to one another comparedwith the states of charge of the rechargeable battery modules 40 in anabsence of the second charge balancing operations.

In the depicted example method, a global average 130 of state of chargemay be determined based upon the states of charge of all of the cells ofboth of the rechargeable battery modules 40. In addition, local averages132 of states of charge of the cells of respective individual modules 40are also shown. The module 40 on the left has a local average 132 lessthan the global average 130 while the module 40 on the right has a localaverage 132 greater than the global average 130.

Referring to the middle illustration of FIG. 8, the example firstbalancing operations balance all of the cells of an individualrechargeable battery module 40 except for one cell. If the local average132 of the module 40 is less than the global average 132, then themodule 40 can receive electrical energy from another module 40 of thepack and the method leaves one cell (A1) undercharged compared with theother cells (A2-A4) which are substantially balanced. If the localaverage 132 of the module 40 is greater than the global average 132,then the module 40 has excess electrical energy which may be transferredto another module 40 and the method leaves one cell (B1) overchargedcompared with the other cells (B2-B4) which are substantially balanced.The above-described first charge balancing operations with respect tobalancing cells in both modules 40 may be simultaneously performed priorto the second charge balancing operations in one embodiment.

Referring in further detail to the middle illustration of FIG. 8,electrical energy from the cell A3 which originally had the higheststate of charge is shuttled to the other cells A1-A2 and A4 providingcells A2-A4 at the global average 130 while electrical energy isshuttled from cells B1 and B4 to cells B2 and B3 providing cells B2-B4at the global average 130. The shuttling of the electrical energy leavescell A1 with a state of charge less than the global average whileleaving cell B1 with a state of charge greater than the global average.

Referring to the bottommost illustration in FIG. 8, electrical energy isshuttled from module B1 to module A1 during second balancing operationswhich reduces the state of charge of cell A1 while increasing the stateof charge of module B1 and providing all of the cells of both of themodules 40 having substantially balanced states of charge at the globalaverage 130. In one embodiment, the capacitor modules 48 of theappropriate modules 40 containing the cells A1-A4 and cells B1-B4 maytransfer the electrical energy from the B1 cell to the A1 cell.

In one implementation, system controller 21 (FIG. 2) is configured toimplement the example method described with respect to FIG. 8. Thesystem controller 21 may access state of charge information regardingcells 12 of a plurality of modules 40 from respective module controllers120, calculate local and global state of charge information, and mayissue commands to the module controllers 120 to implement desiredbalancing operations, for example, based upon states of charge of thecells 12 of the modules 40 (e.g., using the local and global state ofcharge information in one embodiment). Furthermore, system controller 21may communicate status information with respect to outside systems suchas load 14.

As described herein, it is desired to avoid over-charging some types ofrechargeable battery cells 12 and/or to avoid completely draining thecells 12. For example, if Lithium cells are used, overcharging orcompletely draining may damage the cells 12.

In one embodiment, charger circuitry 16 (FIGS. 1 and 2) may utilize aprogrammable power supply which may be controlled by control circuitry20. In some embodiments, an amount of charging electrical energy appliedfrom the charger circuitry 16 to the rechargeable battery cells 12 maybe reduced as the states of charge of the cells 12 increase. In oneembodiment, the control circuitry 20 may monitor voltages of therechargeable battery cells 12 with respect to one or more thresholds asdiscussed above and may reduce an amount of current provided by thecharger circuitry 16 as the voltages of the cells 12 exceed thethresholds indicating that the cells 12 are approaching a fully chargedstate. In one embodiment, the current may be dropped to a level whichmay be safely shunted using the shunting circuitry 62. Differentconfigurations of charger circuitry 16 are possible including voltage orcurrent controlled chargers.

Control circuitry 20 may also monitor the charger circuitry 16 in someembodiments. For example, control circuitry 20 may monitor temperatureduring charging operations, and may control operations of the chargercircuitry 16 to assure proper operation of the charger circuitry 16. Inone example, if the temperature rises above an initial threshold, a fanor cooling system may be controlled in an attempt to reduce thetemperature of the charger circuitry 16. If the temperature of thecharger circuitry 16 reached a higher threshold, the control circuitry20 may implement different operations, such as disabling chargingfunctions until the operational temperature returns to a normaloperational level.

Charge shuttling circuitry 64 may also be used during dischargingoperations of the pack of rechargeable battery cells 12 in an attempt toextract an increased amount of electrical energy from the cells 12compared with arrangements which do not utilize charge shuttlingoperations. As mentioned above, it is desired to avoid completelydraining some types of rechargeable battery cells 12 (e.g., Lithiumcells). Furthermore, some configurations of cells 12 have differentcharge capacities, and accordingly, a cell 12 having a lower chargecapacity may reach a minimum state of charge threshold which is providedto avoid damaging the cells 12 before others of the cells 12 havinghigher charge capacities during discharge operations. In one embodiment,charge shuttling circuitry 64 may be used to shuttle electrical energyfrom one of the rechargeable battery cells 12 having the highest stateof charge to the cell 12 having the lowest state of charge before thecell 12 reaches the minimum state of charge threshold and therebyenabling additional electrical energy to be discharged from the pack ofrechargeable battery cells 12 and increasing the efficiency of theconsumption of the electrical energy in the pack of cells 12.

For some configurations of cells 12 (e.g., cells comprising Lithium),voltages of the cells 12 may rapidly decrease once the cells 12 are inthe discharged state 142. Shuttling of electrical energy to the cell 12having the lowest state of charge allows the battery system 10 to keepthe cell 12 in the relatively flat intermediate state 144 and tomaintain a higher total pack voltage over a longer period of time.Discharge operations may continue until the charge shuttling fails tomaintain all of the cells 12 above the minimum state of charge thresholdat which time discharge operations may be disabled to avoid damaging oneor more of the cells 12 in one embodiment.

At least some embodiments of the disclosure provide improved utilitycompared with other battery system arrangements. For example, use of ahierarchy including control circuitry at different levels, such as thesystem controller and plural module controllers according to someembodiments, may provide improved cost savings for example by having anindividual module controller 120 interfacing with a plurality ofrechargeable cell modules 41. In some embodiments, a relatively largenumber of rechargeable cell modules 41 (e.g., 16 or 32) may be includedwithin a single rechargeable battery module 40 and which communicatewith a single module controller 120. The per-cell cost of a rechargeablebattery module 40 can be determined by dividing by the number ofrechargeable cell modules 41 included within the module 40.

Some arrangements of the disclosure provide include charge balancingcircuits and/or methods to increase the balancing of the states ofcharge of the plural rechargeable battery cells. For example, asdiscussed above in some embodiments, the battery system may use shuntingand/or shuttling operations in attempts to increase the balancing of thestates of charge of the rechargeable battery cells in differentoperational situations of the battery system. In one example, shuttlingof electrical energy with respect to one rechargeable battery cell whichis significantly out of balance compared with others of the cells maydecrease the time needed to balance the cells compared with anarrangement which uses a single balancing procedure, such as shunting.

Shunting may be used to attempt to provide relatively tight balancingbetween the majority of the cells during charging operations asdiscussed above. Some embodiments of the disclosure provide shuntingbalancing operations during a plurality of operational states of therechargeable battery cells (e.g., Lithium cells). For example, shuntingmay be implemented when cells are substantially discharged, in anintermediate states of charge, or substantially discharged. This examplemethod of balancing may provide the cells with states of charge whichare closer together during the charging process compared witharrangements which only implement shunting at the end of the chargingcycle of the cells when the cells are almost fully charged.

Some of the described embodiments may be implemented in modulararrangements which permit the apparatus and methods to be utilized inmany different applications to provide operational energy to manydifferent types of loads having different power requirements. Thesebattery systems may be easily scaled to different applications.Furthermore, one or more module controllers may monitor and controloperations with respect to a plurality of respective rechargeablebattery cells. In some implementations, a higher level system controlmay monitor and control operations of individual ones of the modulecontrollers as discussed herein.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

Further, aspects herein have been presented for guidance in constructionand/or operation of illustrative embodiments of the disclosure.Applicant(s) hereof consider these described illustrative embodiments toalso include, disclose and describe further inventive aspects inaddition to those explicitly disclosed. For example, the additionalinventive aspects may include less, more and/or alternative featuresthan those described in the illustrative embodiments. In more specificexamples, Applicants consider the disclosure to include, disclose anddescribe methods which include less, more and/or alternative steps thanthose methods explicitly disclosed as well as apparatus which includesless, more and/or alternative structure than the explicitly disclosedstructure.

1-14. (canceled)
 15. A rechargeable battery system comprising: aplurality of rechargeable battery cells coupled between a plurality ofterminals; and charger circuitry configured to provide chargingelectrical energy to the rechargeable battery cells to charge therechargeable battery cells, and wherein the charger circuitry isconfigured to reduce an amount of the charging electrical energyprovided to charge at least the one of the rechargeable battery cellswhich has a highest state of charge compared with others of therechargeable battery cells as a result of the state of charge of the oneof the rechargeable battery cells exceeding a threshold.
 16. The systemof claim 15 further comprising shunt circuitry configured to shuntelectrical energy around the one of the rechargeable battery cells as aresult of the state of charge of the one of the rechargeable batterycells exceeding the threshold.
 17. The system of claim 16 wherein theshunt circuitry is configured to continually shunt the electrical energywithout modulation as a result of the state of charge of the one of therechargeable battery cells exceeding the threshold.
 18. The system ofclaim 16 wherein the shunt circuitry is configured to cease the shuntingas a result of a temperature of the shunt circuitry exceeding athreshold.
 19. The system of claim 15 wherein the charger circuitry isconfigured to reduce an amount of the charging electrical energyprovided to charge all of the rechargeable battery cells as a result ofthe state of charge of the one of the rechargeable battery cellsexceeding the threshold.
 20. The system of claim 15 wherein the chargercircuitry reduces the charging electrical energy provided to charge theone of the rechargeable battery cells by different amounts correspondingto the state of charge of the one of the rechargeable battery cellsexceeding respective ones of a plurality of different thresholdsincluding the threshold.
 21. The system of claim 20 wherein the chargercircuitry ceases the provision of the charging electrical energy tocharge the one of the rechargeable battery cells as a result of thestate of charge of the one of the rechargeable battery cells exceedingone of the different thresholds.
 22. The system of claim 15 wherein therechargeable battery system comprises a plurality of modules, and one ofthe modules comprises the rechargeable battery cells, and the other ofthe modules individually comprise a plurality of additional rechargeablebattery cells.
 23. A rechargeable battery system operational methodcomprising: providing charging electrical energy to a plurality ofrechargeable battery cells to charge the rechargeable battery cells; andreducing an amount of the charging electrical energy provided to one ofthe rechargeable battery cells which has a highest state of chargecompared with others of the rechargeable battery cells; and wherein thereducing comprises reducing the amount of the charging electrical energyprovided to the one of the rechargeable battery cells by differentamounts at different moments in time as a result of the state of chargeof the one of the rechargeable battery cells exceeding respective onesof a plurality of different thresholds.
 24. The method of claim 23wherein the providing comprises providing the charging electrical energyusing charger circuitry, and wherein the reducing comprises reducing theamount of the charging electrical energy using the charger circuitry.25. The method of claim 23 further comprising shunting at least some ofthe charging electrical energy around the one of the rechargeablebattery cells.
 26. The method of claim 25 wherein the shunting comprisescontinually shunting without modulation.
 27. The method of claim 25wherein the shunting comprises shunting using shunting circuitry, andfurther comprising ceasing the shunting as a result of a temperature ofthe shunting circuitry exceeding a threshold.
 28. The method of claim 23wherein the reducing comprises reducing the amount of the chargingelectrical energy provided to all of the rechargeable battery cells as aresult of the state of charge of the one of the rechargeable batterycells exceeding one of the thresholds.
 29. (canceled)
 30. The method ofclaim 23 wherein the reducing comprises ceasing the provision of thecharging electrical energy to the one of the rechargeable battery cellsas a result of the state of charge of the one of the rechargeablebattery cells exceeding one of the different thresholds.